WINDHAM – Constructing a sewer for North Windham and Windham Center could cost around $67 million, the Windham Town Council was told Tuesday night.

But, councilors were also told the project could cost a lot less or a lot more.

According to Woodard & Curran engineering consultant Barry Scheff, the $67 million price tag is only an estimate based on broad assumptions and contingent on many factors, such as whether the town could secure grants to help fund the project. The actual price, he said, could be up to 30 percent less than the projected $67 million or 50 percent more, depending on underground conditions which are now mostly unknown.

In addition to the upfront costs, Scheff estimates yearly operations and maintenance costs at $460,000.

Scheff, whose company received $25,800 to conduct the initial survey, also referred to groundwater surveys for North Windham indicating rising levels of nitrates. Those pollutants could affect the North Windham aquifer and well water for area residents, he said.

“You have a trend that you’re experiencing where groundwater concentrations are increasing in terms of nitrate/nitrogen, and that’s a public health risk,” Scheff said.

In addition to the public health and resource protection concerns, a sewer would help community and economic development, Scheff said. With North Windham considered the Lakes Region’s commercial hub, groundwater contamination – which has been tracked for 12 years since the former Christy’s gas station experienced an MTBE leak – could be alleviated with the introduction of a wastewater system that new and existing businesses and residents in the area could use. Now, 700,000 gallons of water are being discharged into the aquifer daily, he said.

Also discussed Tuesday night was a possible alliance between the city of Westbrook and the town of Windham in paying for a new sewer.

Windham’s current plan is to run the sewer line down Route 302 to East Bridge Street and into the Portland Water District’s wastewater treatment facility. Westbrook’s water line currently ends at Prides Corner, Scheff said. A Windham-Westbrook partnership could therefore bring sewer to residents and businesses on Route 302 in Westbrook above Prides Corner. Councilors made little comment on this aspect, since negotiations are ongoing.

The engineering plans also revealed the scope of the proposed sewer, which would serve a total of 5,800 parcels. The system of collection pipes would extend from the Raymond line in North Windham through the commercial district and south along River Road, Windham Center Road and Route 302 to include the high school complex. It would also include northeast areas of Windham to the Gray town line. The sewer would not serve East Windham or South Windham. In all, the sewer would encompass 16.9 square miles.

Other important considerations that could impact cost – including whether non-users would help pay for the system through property tax or whether residents would be required to connect, are issues that will be determined as the council deliberates.

At numerous times throughout Tuesday’s discussions, councilors spoke of the need for public input. The next step is a public hearing to discuss the plans as drafted so far. That hearing could occur as early as next Tuesday, Aug. 10. The council agenda is available on the town’s website prior to the meeting.